Comparison of definitive radiotherapy outcomes between younger and older patients with high- or very-high-risk prostate cancer.

Abstract

This study aimed to compare the oncologic outcomes of definitive intensity-modulated radiotherapy (IMRT) between younger and older high- or very-high-risk prostate cancer patients using propensity score matching (PSM) and competing risk analysis (CRA). A total of 569 patients were included in this analysis: 265 younger than 75 years (Group A) and 304 aged 75 years or above (Group B). All patients received IMRT with a daily fraction of 2.2 Gy, administered over 34 fractions, resulting in a total dose of 74.8 Gy. The primary outcomes included biochemical-failure-free survival (BCFFS), distant-metastasis-free survival (DMFS), clinical-failure-free survival (CFFS), cancer-specific survival (CSS), and overall survival (OS). PSM was used to balance the groups, employing a full matching method, while CRA distinguished between cancer-specific events and non-cancer-specific events. Before PSM, the 7-year BCFFS, DMFS, CFFS, CSS, and OS rates in Groups A and B were 83.0 % vs. 66.7 % (p = 0.011), 84.1 % vs. 68.0 % (p = 0.002), 82.1 % vs. 66.7 % (p = 0.008), 95.6 % vs. 97.3 % (p = 0.704), and 87.4 % vs. 68.6 % (p < 0.001), respectively. After PSM, the 7-year survival rates were comparable between both groups for all outcomes except OS. CRA revealed that cancer-specific events were more frequent in Group A, whereas non-cancer-specific events predominated in Group B. Both PSM and CRA indicated that definitive IMRT can be safely and effectively delivered to older patients with high- or very high-risk prostate cancer, achieving oncologic outcomes comparable to those in younger patients.